IANA and JDK-specific character encoding names

First, of all IANA keeps a registry of character set (character encoding)
names. It can accessed
here.

Second, JDK docs include a list of character encodings
supported by the JDK. For JDK 1.3 this can be accessed
here
or in your own tree of JDK documents at docs/guide/intl/encoding.doc.html.

(As this doc says, these encodings are supported if you have the
jre/lib/i18n.jar in your distribution.

This list of supported encodings
lists encodings by their canonical names.

Canonical name of a character encoding is the value
returned by the getEncoding
method in the
java.io.InputStreamReader
and java.io.OutputStreamWriter
classes. The character sets in JDK 1.3 may have aliases
and if the java.io.InputStreamReader/
java.io.OutputStreamWriter has been
given a character set name alias at creation time then
the java.io.InputStreamReader will
still return the canonical name.

Canonical names are not always the same as
IANA preffered names for the character encodings,
but IANA preffered character encoding names are recognised as
aliases to the canonical names.
For example,

the IANA preffered character encoding name is

while JDK canonical name is

UTF-8

UTF8

ISO-8859-1

ISO8859_1

Shift_JIS

SJIS

KOI8-R

KOI8_R

It might be worth noting that xerces
sources contain a special utility function that performs conversions of the form
UTF-8 -> UTF8 and there's some wording there
about JDK 1.1

So we can suspect that JDK 1.1 did not support the IANA preffered names
as aliases for all the character encodings that it had support for.